The iPhone 6s is selling like hotcakes, on pace to beat Apple’siPhone 6 sales record, at least according to what the company is saying. The phone became available in Apple and carrier stores around the world on Friday, and while millions of buyers are already getting used to 3D Touch and a new iOS interaction model, a fresh set of iPhone 7 rumors may offer some details about Apple’s plans for next year’s iPhones.

According to Macotakara, the iPhone 7 is well into the prototyping phase, with Apple trying out a brand new design. These iPhone 7 test units are waterproof and dust-proof, and Apple is even considering ditching the aluminum shell for next year’s iPhone.

In the past, Apple used plastic and glass for its iPhones, always focusing on increasing build quality and durability. Starting with the iPhone 5, Apple replaced the glass with aluminum on all models — the exception being the plastic iPhone 5c. The iPhone 6 and iPhone 6s also have metal shells, with this year’s iPhone being made of durable “bendgate”-resistant 7000 Series metal.

Finally, the Japanese tech site says that the iPhone 7 will have an entirely flat LCD, suggesting the handset won’t feature the same “2.5D” glass as the iPhone 6 and iPhone 6s, which has rounded corners.

Actual images showing Apple’s alleged iPhone 7 prototypes aren’t available at this time. It should be noted that Apple is known to try out a variety of designs and concepts before landing on a new iPhone design, so it wouldn’t be surprising to hear other “crazy” iPhone 7 rumors in the coming months.